An Item Retrieval Algorithm in Flexible High-Density Puzzle Storage Systems

This paper studies a design of a puzzle-based storage system. We developed an item retrieval algorithm for our system which has three advantages over the previous counterparts in the literature: (i) we can retrieve items from all sides of our storage system; (ii) the existence of only one empty cell in our system is sufficient to retrieve an item; and (iii) our algorithm never ends in deadlocks. The main feature of our algorithm is to prefer three moves to five moves in the process of moving the seized empty cell toward the optimal side of the requested item. The conventional view in the literature assumes that increasing the number of empty cells always reduces the number of movements required for retrieving items; however, our simulation results show that depending on the size of the puzzle and the number of the requested items, increasing empty cells might make the retrieval process more complicated.

Decay, insect, and termite resistance of wood modified with epoxidized vegetable oils

Samples of Scots pine sapwood were treated with epoxidized linseed and soybean oils to improve decay, insect and termite resistance of wood. Non-epoxidized (raw) linseed and soybean oils were included as reference treatment in the study. In the epoxidation process, hydrogen peroxide was used to open double bounds, and acetic acid was added as a catalyst. Two retention levels, Ret A (80–140 kg m−3) and Ret B (170–270 kg m−3), two impregnation methods (full cell and empty cell) and emulsion technique were used. Samples treated with epoxidized oils had significantly lower mass losses than untreated samples while epoxidized oils showed higher mass losses than unepoxidized oils for Coniophora puteana and Trametes versicolor according to EN 113 for decay test. By adding boron, fungicidal properties were introduced to the treatment. All the vegetable oils showed 100% the mortality rate against larvae of Hylotrupes bajulus according to EN 47. Moreover, leached wood samples treated with oils also showed 100% larvae mortality. Additionally, termite testing based on EN 117 revealed 100% Reticulitermes lucifugus mortality for all leached oil treated samples.

Optimal dynamic routing for two forklifts in narrow-Aisle racking warehouse

Determining storage location and planning path are the two most important components in warehouse management. Simultaneous resolution of these problems not only reduces the storage and retrieval time but also avoids the loss of goods. The article offers a scenario of a practical cold warehouse system with narrow aisle racking, where space optimization and time schedules are always the top priority. There are two forklifts considered to work parallel in the system, so aisle dispute is considered to minimize safety risks in the warehouse. Two algorithms used to optimize the path were introduced in the paper, which is the closest open location – COL and A star algorithm. The COL helps to determine the most appropriate storage location according to the user's requirements, including the type of goods to be exported or imported, finding storage location of the nearest empty cell by referring the weight of the road and obstacle might happen by two forklift truck in the system. The result of this algorithm is the determined Input and Output point of each forklift path. The coordinate index ​​of these two points is returned as input to the A-star algorithm to determine the shortest path for the forklift. With the A star algorithm, a clear path will be sought, including the comparison of clashes between vehicles in the system, preferring the shortest path for moving between two points. The travel route results are exported for goods execution devices. The system is simulated by MATLAB combined with V-Rep software for an intuitive interface and fully illustrates each task of each vehicle from time to time. Some traditional or single algorithms with the same assumptions about the system were also simulated and compared to see the effectiveness of the combination of two COL and A star algorithms in a narrow aisle racking system.

Restricted completion of sparse partial Latin squares

Ann×npartial Latin squarePis calledα-dense if each row and column has at mostαnnon-empty cells and each symbol occurs at mostαntimes inP. Ann×narrayAwhere each cell contains a subset of {1,…,n} is a (βn,βn, βn)-array if each symbol occurs at mostβntimes in each row and column and each cell contains a set of size at mostβn. Combining the notions of completing partial Latin squares and avoiding arrays, we prove that there are constantsα,β> 0 such that, for every positive integern, ifPis anα-densen×npartial Latin square,Ais ann×n (βn, βn, βn)-array, and no cell ofPcontains a symbol that appears in the corresponding cell ofA, then there is a completion ofPthat avoidsA; that is, there is a Latin squareLthat agrees withPon every non-empty cell ofP, and, for eachi,jsatisfying 1 ≤i,j≤n, the symbol in position (i,j) inLdoes not appear in the corresponding cell ofA.

Kajian Masalah Transshipment Tidak Seimbang Menggunakan Metode Least Cost - Stepping Stone Dan Metode Least Cost - Modi

Penelitian ini merupakan kajian masalah transshipment tidak seimbang menggunakan metode Least Cost - Stepping Stone. Metode Least Cost - MODI juga digunakan untuk membandingkan uji optimalitas mana yang lebih baik dalam menyelesaikan masalah transshipment ini. Hasil dari penelitian menunjukkan bahwa metode Least Cost - SteppingStone dan metode Least Cost - MODI dapat menyelesaikan masalah transshipment tidak seimbang. Menurut uji perbandingan metode MODI lebih efisien dari pada metode Stepping Stone dalam menguji optimalitas suatu masalah transshipment karena metode MODI memerlukan lebih sedikit iterasi dibandingkan dengan metode Stepping Stone. Pada Metode MODI nilai indeks perbaikan dapat dicari tanpa harus mencari loop dari setiap sel kosong, yakni hanya membutuhkan satu loop yang didapat setelah menentukan sel dengan indeks perbaikan terbesar, sedangkan pada metode Stepping Stone nilai indeks perbaikan dicari dengan membuat loop untuk setiap sel kosong pada setiap iterasi. Selain itu Metode Least Cost menghasilkan biaya transportasi yang berbeda apabila posisi penempatan biaya diubah, sedangkan dengan metode Stepping Stone biaya transportasi akan tetap sama dan optimal apabila posisi penempatan biaya diubah. This research is a study of unbalanced transshipment problems using the Least Cost - Stepping Stone method. The Least Cost - MODI method was also used to compare which optimality test was better in solving this transshipment problem. The results of the study showed that the Least Cost - Stepping Stone method and the Least Cost - MODI method could solve unbalanced transshipment problems. According to the comparison test, the MODI method was more efficient than the Stepping Stone method in testing the optimality of a transshipment problem because the MODI method required less iteration than the Stepping Stone method. In the MODI method, the repair index value could be searched without having to search for loops from each empty cell, which only requires one loop after determining the cell with the largest repair index. On the other hand, in the Stepping Stone method, the repair index value was searched by making a loop for each empty cell at each iteration. In addition, the Least Cost method produced different transportation costs if the placement position costs were changed. Meanwhile, the Stepping Stone method transportation costs would remain the same and optimal if the placement position costs were altered.

CCB Preservative Treatment of Acacia mangium Poles by Pressure Process

A study was conducted on the preservative treatment of Acacia mangium poles to determine the treatment schedule for outdoor use. The poles contained 52.27% sapwood which is generally perishable by wood destroying organisms. In this study, 27 poles were treated with aqueous solution of 10% CCB by Lowry empty cell process. Three different pressures and three time periods were applied to evaluate the depth of penetration and amount of retention of the preservative chemicals. It was observed that preservative chemicals penetrated the entire sapwood portions of the poles which are the main criteria for the protection of poles. But, on the other hand, no significant increase was observed in penetration with the simultaneous increase of pressure and time period, although the retention of the preservatives was found to increase significantly. The highest retention of 22.98 kg/m3 and full penetration of sapwood was observed after 1.04 N/mm2 pressure for three hours. It is expected that the applied pressure and time period are adequate for protecting the Acacia mangium poles from wood destroying organisms in outdoor condition.

Collision Detection for Point Cloud Models With Bounding Spheres Hierarchies

Point cloud models are a common shape representation for several reasons. Three-dimensional scanning devices are widely used nowadays and points are an attractive primitive for rendering complex geometry. Nevertheless, there is not much literature on collision detection for point cloud models. This paper presents a novel collision detection algorithm for large point cloud models using voxels, octrees and bounding spheres hierarchies (BSH). The scene graph is divided in voxels. The objects of each voxel are organized intoan octree. Due to the high number of points in the scene, each non-empty cell of the octree is organized in a bounding sphere hierarchy, based on an R-tree hierarchy like structure. The BSH hierarchies are used to group neighboring points and filter out very quickly parts of objects that do not interact with other models. Points derived from laser scanned data typically are not segmented and can have arbitrary spatial resolution thus introducing computational and modeling issues. We address these issues and our results show that the proposed collision detection algorithm effectively finds intersections between point cloud models since it is able to reduce the number of bounding volume checks and updates

A Review of IS Research Activities and Outputs Using Pro Forma Abstracts

Using March and Smith’s taxonomy of information systems (IS) research activities and outputs and Newman’s method of pro forma abstracting, this research mapped the current space of IS research and identified research activities and outputs that have received very little or no attention in the top IS publishing outlets. We reviewed and classified 1,157 articles published in some of the top IS journals and the ICIS proceedings for the period 1998–2002. The results demonstrate the efficacy of March and Smith’s (1995) taxonomy for summarizing the state of IS research and for identifying activity-output categories that have received little or no attention. Examples of published research occupying cells of the taxonomy are cited, and research is posited to populate the one empty cell. The results also affirm the need to balance theorizing with building and evaluating systems because the latter two provide unique feedback that encourage those theories that are the most promising in practice.